Research Letter—Outcomes of Outpatient Native Kidney Biopsies at the McGill University Health Center: A Quality Assurance Audit

Background: Percutaneous kidney biopsies are essential for diagnosis and management of kidney diseases. However, post-procedural bleeding is a significant risk associated with biopsies. At the McGill University Health Center, the 2 main hospitals, the Royal Victoria Hospital and the Montreal General Hospital, have different observation protocols for outpatient native kidney biopsies. Currently, patients are admitted for a 24-hour inpatient observation at the Montreal General Hospital, whereas patients biopsied at the Royal Victoria Hospital are discharged after 6 to 8 hours of observation at the end of the day. Most Canadian centers do not admit patients for an overnight observation, and it was unclear why this practice continued at the Montreal General Hospital. Objective: Our objective was to determine the incidence of complications post-renal biopsy over the past 5 years at both hospital sites, and compare them to each other, as well as to established rates in the available literature. Design: This assessment was designed as a quality assurance audit. Setting: This audit was conducted from a local registry of renal biopsies performed at the McGill University Health Center between January 2015 to January 2020. Patients: We included all adult patients (between the ages 18 and 80) with outpatient native kidney biopsies performed at the McGill University Health Center between 2015 and 2020. Measurements: We collected the included patients’ baseline demographics and risk factors at the time of biopsy, including age, BMI, creatinine, estimated glomerular filtration rate, pre- and post-biopsy hemoglobin, platelet, urea, coagulation profile, blood pressure, kidney side/size as well as needle size, and number of passes made. Methods: We compared the incidence of both minor and major bleeding complications at the Montreal General and the Royal Victoria Hospital. Variables that were measured included hemoglobin before and after biopsy, incidence of minor bleeding complications (defined by hematomas and gross hematuria), and incidence of major complications (defined by post-biopsy bleeding requiring either transfusions or another procedure to stop the bleeding), as well as the incidence of admissions post-biopsy. Results: The incidence of major complications was 2.87% over 5 years (5/174 patients), which is comparable with that reported in the literature. Our transfusion incidence was 1.72% (3/174 patients) and our embolization incidence was 2.3% (4/174 patients) over the 5 study years. Our total number of major events was low and the patients who had major events had significant risk factors for bleeding. All events occurred within 6 hours of observation. Limitations: This was a retrospective study with a low event number. Additionally, since the events included only those recorded at the McGill University Health Center, it is possible that the events of interest may have occurred at other hospital sites without the author’s knowledge. Conclusions: Based on the results of this audit, all major bleeding events occurred within 6 hours of a percutaneous kidney biopsy, suggesting that patients should be monitored for 6 to 8 hours following biopsy. The next step after this quality assurance audit is a quality improvement project and a cost-effectiveness analysis to assess whether post-biopsy practices should be amended at the McGill University Health Center

Biochemical analysis of patients with mutations in MTHFD1 and a diagnosis of methylenetetrahydrofolate dehydrogenase 1 deficiency

MTHFD1 is a trifunctional protein containing 10-formyltetrahydrofolate synthetase, 5,10-methenyltetrahydrofolate cyclohydrolase and 5,10-methylenetetrahydrofolate dehydrogenase activities. It is encoded by MTHFD1 and functions in the cytoplasmic folate cycle where it is involved in de novo purine synthesis, synthesis of thymidylate and remethylation of homocysteine to methionine. Since the first reported case of severe combined immunodeficiency resulting from MTHFD1 mutations, seven additional patients ascertained through molecular analysis have been reported with variable phenotypes, including megaloblastic anemia, atypical hemolytic uremic syndrome, hyperhomocysteinemia, microangiopathy, infections and autoimmune diseases. We determined the level of MTHFD1 expression and dehydrogenase specific activity in cell extracts from cultured fibroblasts of three previously reported patients, as well as a patient with megaloblastic anemia and recurrent infections with compound heterozygous MTHFD1 variants that were predicted to be deleterious. MTHFD1 protein expression determined by Western blotting in fibroblast extracts from three of the patients was markedly decreased compared to expression in wild type cells (between 4.8 and 14.3% of mean control values). MTHFD1 expression in the fourth patient was approximately 44% of mean control values. There was no detectable methylenetetrahydrofolate dehydrogenase specific activity in extracts from any of the four patients. This is the first measurement of MTHFD1 function in MTHFD1 deficient patients and confirms the previous molecular diagnoses